Daniel, Alexa, Sheila

We have tried to measure the green modulation depth of the X arm by moving the modulation frequency (24.410610MHz) so that the sidebands are antiresonant in the cavity, and then locking the cavity on the carrier (+polarity on servo board) then the sidebands.  We used H1:ALS-C_COMM_A_LF_OUTPUT to measure the transmitted power.

I have changed the offset to -66 counts, so that with no light on the PD we get zero counts (-0.26 counts)  (someone had changed this from the -61 I originally set to -100 sometime last week, I am not sure why).  With the single shot beam we get 46.06 counts.

Below are plots ot the transmitted powers (normalized) when locked on the carrier and sideband, and the second plot is their ratio.  I used the ratio to do a simple fit for the modulation depth that we started with, and got 0.80  Now the modulation frequency is restored to the nominal 24.407079MHz and the 12dB attenuator is in place so our modulation depth should be 0.2.

Also, the ratio of the transmitted power on resonance/ single shot beam should be:

1/(1-sqrt(R1*R2))^2=22.6 for a perfectly mode matched carrier with R1=0.63, R2=0.99, taking into account the 0.2 modulation depth we would expect 22.17.  Since we curently measure a ratio of 14.4 between the single shot and locked trans power, which is 65% of what we would expect.  This means we have about 45% of our power in higher order modes. 

Daneil's alog about the RF powers is 9484

Writing of 64 second full frames has started on h1fw0.

We were measuring the green modulation depth in EX by looking at the transmitted power when locking the cavity on carrier or sidebands. To make the interpretation easier we first used the ifr to move the sidebands to exactly mid-fringe. With a length of 3994.472 m and a multiple of 650.5 we get a frequency of 24.410610 MHz. The ifr was set to +11 dBm for the measurement.

Here we report the measured RF levels. We used an Agilent N1914A with probe E4412A (S/N MY50270005). A zero check and calibration was performed before the measurement. An attenuator was added at the RF patch panel in the field rack between the balun and the cable driving the Pockels cell. As a comparison we list the attenuation values measured with the RF source at a frequency of 24.407079 MHz as well. We left the 12 dB attenuator installed and switched back to the RF source.

The h1nds0 daqd will be shut down for up to 10 minutes to build RCG 2.8.2 versions of daqd to support longer frames.  Longer frame collection should be implemented about 11:00 PST for h1fw0.  Following about an hour of testing, and assuming testing is successful, longer frame writing will be implemented on h1fw1 about 12:00 PST.  

HAM4 and HAM5 are different compared to HAM236, because of the ST0-L4Cs. Consequently, we need to use the proper blocks for the BIO cards.

The changes have been made (see pic attached), the models recompiled and restarted. Everything went fine.

@9:45